JP2010135361A - Negative electrode, lithium ion capacitor, and manufacturing method of them - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a negative electrode, a lithium ion capacitor and manufacturing methods of them, in which manufacturing processes are simple, productivity is superior, and internal resistance is small to make a large current flow, compared with a conventional lithium ion capacitor. <P>SOLUTION: The negative electrode, which has a negative electrode active substance layer on at least one surface of a negative electrode collector foil with almost the same area, is characterized by being formed with at least one slit by extending so as to include the component of a length direction only in the negative electrode collector foil. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a negative electrode, a lithium ion capacitor, and a manufacturing method thereof.

  The existing electric double layer capacitor has a sheet-like positive electrode and negative electrode made of carbon material such as activated carbon and a binder, a porous separator that electrically insulates both electrodes, and a cylindrical type made of metal such as stainless steel and aluminum. Alternatively, it is composed of a rectangular container and an electrolyte filled in the container and impregnated in both electrodes and a porous separator, and the capacitance of the electric double layer generated at the interface between both electrodes and the electrolyte is contained in the electrolyte. The ions are charged and discharged by moving between the electrodes. Since this electric double layer capacitor does not involve an electrochemical reaction, it has excellent charge / discharge rate characteristics and cycle characteristics. For this reason, it is used as a backup power source for electronic devices and as a battery for various transport aircraft including automobiles. However, the problem is that the energy density is lower than that of the battery.

Similarly, in the lithium ion secondary battery that has existed for a long time, the positive electrode is generally made of a lithium-containing metal oxide such as LiCoO ₂ , and the negative electrode is made of a carbon material such as graphite. Lithium ion insertion and desorption reactions are used in which lithium is supplied to the negative electrode and lithium in the negative electrode is returned to the positive electrode during discharge. Since this battery has a high voltage and high energy density, it is widely used in power supplies for portable devices, electric tools, home appliances, and the like. However, while the energy density is high, there are problems in terms of output characteristics, cycle characteristics, and safety.

  Therefore, in recent years, a power storage device called a lithium ion capacitor (hereinafter referred to as LIC) that combines the power storage principles of a lithium ion secondary battery and an electric double layer capacitor has been attracting attention and its development has been actively conducted. In this LIC, a hybrid type using a carbon material such as activated carbon which is a positive electrode active material of an electric double layer capacitor as a positive electrode and a carbon material such as graphite as a negative electrode active material of a lithium ion secondary battery as a negative electrode. Capacitor.

  In LIC, a carbon material that can occlude and desorb lithium ions is previously occluded and supported (dope or doped; hereinafter referred to as dope) by a chemical method or an electrochemical method to lower the negative electrode potential. Can greatly increase the energy density. There is an invention in which the opposing area of the lithium ion supply source and the negative electrode is 75% or more and less than 100% of the negative electrode area, so that the negative electrode can be doped with lithium ions without leaving the lithium ion supply source in the cell ( For example, see Patent Document 1).

  The negative electrode is provided with an electrolyte together with a positive electrode and a negative electrode, and the negative electrode is provided on both sides of the strip-shaped negative electrode current collector and the negative electrode current collector, and includes at least one of silicon and tin as a constituent element. The negative electrode current collector and the negative electrode active material layer have a material layer, and the penetrating part cut out or cut through the negative electrode current collector and the negative electrode active material layer includes a longitudinal component of the negative electrode current collector. Thus, there is an invention related to at least one battery (see, for example, Patent Document 2).

JP 2006-286919 A (Claim 1, FIG. 3) JP 2007-280665 A (Claim 1, FIG. 2)

  In the invention according to Patent Document 1, a porous material (expanded metal, punched metal, etc.) is used for the negative electrode current collector and the positive electrode current collector, and the lithium ion dope source such as metallic lithium is in electrochemical contact with each electrode. By doing so, lithium ions can freely move between the electrodes from the end of the electrode stack through the through holes of both current collectors, and all the negative electrodes of the electrode stack can be doped with lithium ions. Yes. When the porous material is used as a current collector, the cross-sectional area of the conductive part is significantly reduced and the electric resistance is increased as compared with the case where a smooth metal foil used in a general LIC is used. For this reason, there is a drawback that it is difficult to flow a large current, which is a characteristic of LIC.

  In addition, when using a porous material with a large aperture ratio for the current collector, a smooth electrode layer cannot be obtained by applying the paste electrode mixture on the current collector once, and the electrode surface is uneven. Can cause deterioration of charge / discharge characteristics. On the other hand, a plurality of coatings have been proposed in which a hole is filled by the first coating (sealing coating), and a smooth electrode having a predetermined thickness is obtained by two or more repeated coatings. The process is complicated, and the defect rate increases with the number of processes.

  The invention according to Patent Document 2 has a structure in which a through-hole cut into the negative electrode after press working is formed, so that the aperture ratio is small and it takes time to dope lithium ions, and the dope is insufficient. Therefore, there is a drawback that a sufficient charge / discharge capacity cannot be obtained. In addition, when taking a structure that forms a cut-through part that penetrates the negative electrode, not only the cutting process becomes complicated, but also the work of changing the cut-out area corresponding to the change in the negative electrode area becomes complicated, and the negative electrode There was a drawback that it was not possible to flexibly respond to changes in area.

  The present invention has been made to solve such a problem, and has a simple manufacturing process, excellent productivity, a small internal resistance and a large current flow, and a negative electrode having good charge / discharge characteristics. It is an object of the present invention to provide a LIC and a manufacturing method thereof.

  The negative electrode according to the present invention is a negative electrode in which a negative electrode active material layer is provided on at least one surface of a negative electrode current collector foil with substantially the same area, and at least one slit having a longitudinal component only in the negative electrode current collector foil. It is characterized by being formed.

  According to this invention, after forming a slit in the negative electrode current collector foil in advance and forming the negative electrode active material layer, the width of the penetrating portion is expanded and the slit is formed by pressing at a predetermined temperature and pressure. Therefore, it is possible to provide a negative electrode, an LIC, and a method for manufacturing the same, which can easily input and output a large current and can improve rate characteristics, despite a simple manufacturing process corresponding to mass production with excellent productivity. be able to.

Embodiment 1 FIG.
FIG. 1 is a diagram showing a part of a cross section of a lithium ion capacitor (hereinafter sometimes referred to as LIC) in Embodiment 1 of the present invention. In the figure, a positive electrode active material layer 2 in which a positive electrode material and a conductive additive are bound with a binder is applied to one side of a belt-like positive electrode current collector foil 1 to form a positive electrode 3. A negative electrode active material layer 6 in which a negative electrode material and a conductive additive are bound with a binder is applied to one side of a strip-shaped negative electrode current collector foil 5 having slits 4 to form a negative electrode 7. Here, although the positive electrode current collector foil 1 and the negative electrode current collector foil 5 are strip-shaped, they may be substantially rectangular or substantially square. In addition, since it is shaped by press working described later, there may be some variation in width and the like.

  In the positive electrode 3 and the negative electrode 7, the center line of the short side of the strip-shaped positive electrode current collector foil 1 and the center line of the short side of the strip-shaped negative electrode current collector foil 5 substantially coincide, and the positive electrode active material layer 2 and the negative electrode active material layer 6 are opposed to each other with an electronic insulating and porous separator 8 therebetween. Further, a lithium metal (lithium electrode) 9 as a lithium ion supply source is arranged opposite to the negative electrode current collector foil 5 through an electronic insulating and porous separator 8.

  Here, the positive electrode 3, and the constituent parts formed by laminating the separator 8 provided between the positive electrode active material layer 2 and the negative electrode active material layer 6, as necessary, may include a positive electrode layer 10, a negative electrode 7, and A component formed by laminating a separator 8 provided between the negative electrode current collector foil 5 and the lithium metal 9 is referred to as a negative electrode layer 11 as necessary. The laminated positive electrode 3 is connected to the positive electrode connection terminal 13 by, for example, welding by the positive electrode extraction part 12, and the negative electrode 7 and the lithium metal 9 are respectively connected to the negative electrode connection terminal 16 by the negative electrode extraction part 14 and the lithium doped electrode extraction part 15. It is connected. Here, the LIC cell 18 is a state in which the positive electrode layer 10, the negative electrode layer 11, and the lithium metal 9 are laminated and the electrode terminals and the like are attached and before being housed in the outer container 17. In the present embodiment, the positive electrode connection terminal 13 and the negative electrode connection terminal 16 are provided at the left end and the right end of the LIC cell 18 as shown in FIG. 1, but the positions of these connection terminals can be changed as appropriate. . In addition, in FIG. 1, the exterior container 17 has shown the outline in the dotted line.

  In this embodiment, the positive electrode 3 and the negative electrode 6 are formed by coating the positive electrode active material layer 2 and the negative electrode active material layer 6 on one side of the strip-like positive electrode current collector foil 1 and the negative electrode current collector foil 5, respectively. However, it does not necessarily have to be one side, and as shown in FIG. 3, it may be formed by being applied to both sides or both sides of one of the poles.

  FIG. 2 is a sectional view showing the structure of the LIC cell 18 in the first embodiment of the present invention. FIG. 1 shows the minimum structural unit as the LIC cell 18, but as shown in FIG. 2, the positive electrode layer 10, the negative electrode layer 11, and the lithium metal 9 are alternately arranged in order to accumulate the capacity necessary for the LIC. It is common to have a laminated structure. In FIG. 2, the LIC cell 18 is composed of a total of nine layers of three positive electrodes 3, three negative electrodes 7, and three layers of lithium metal 9 in terms of the number of active material layers. The number of layers of the positive electrode 3 and the negative electrode 7 is not specified depending on the type of the LIC cell 18, the number of layers of the lithium metal 9 disposed in the LIC cell 18, and the like. Usually, the total number of the positive electrode layer 10 and the negative electrode layer 11 is about 5 to 20 layers. Further, here, assuming that the positive electrode 3 is not a porous layer, the lithium metal 9 is provided for each of the positive electrode layer 10 and the negative electrode layer 11, but the positive electrode 3 is made of a porous material through which lithium ions can pass. In this case, only one layer of lithium metal 9 may be provided on the bottom or top of the LIC cell 18. Furthermore, the LIC cell 18 may be accommodated in the outer container 17 in either the vertical direction or the horizontal direction.

  In addition to the structure described above, in this embodiment, the positive electrode 3 may be opposed to the negative electrode 7, and the separator 8 impregnated with the electrolyte solution may be present between the positive and negative electrodes. For example, a laminated structure in which a plurality of flat electrodes are stacked, a wound structure in which strip-shaped electrodes are wound, or a folded structure in which strip-shaped electrodes are folded and stacked. Moreover, you may make the composite structure which combined these.

  Further, the connection terminal connected to the current collector portion of the LIC is not particularly limited as long as it is a conductive material that stably exists in the LIC.

  In the LIC cell 18, the outermost part (lower part in FIG. 1) on the side where the lithium metal 9 is disposed is the separator 8, and the negative electrode 7 is preferably disposed inside thereof. By using the separator 8 as the outermost part of the LIC cell 18, it is possible to prevent the lithium metal 9 from coming into direct contact with the electrode and prevent damage to the electrode surface due to rapid dope after the electrolyte is injected. Further, when the LIC cell 18 is previously made outside and then installed in the outer container 17, the electrode can be covered with the separator 8 for protection. Further, by making the inner side of the separator 8 the negative electrode 7, there can be obtained an advantage that there is no problem even if the negative electrode 7 and the lithium metal 9 are short-circuited.

  FIG. 4 is a cross-sectional view showing an example of the winding structure of the LIC in the first embodiment of the present invention. FIG. 2 shows a structure in which the positive electrode layers 10 and the negative electrode layers 11 are alternately laminated. As shown in FIG. 4, the belt-like positive electrode layer 10 and the belt-like negative electrode layer 11 are laminated and wound. By doing so, a layered structure (winding structure) may be taken. In FIG. 4, the positive electrode connection terminal 13 and the negative electrode connection terminal 16 are provided in the center of each film-type LIC cell 18, but the positions of these connection terminals can be changed as appropriate.

  Further, the LIC shown in FIG. 4 has a wound structure in which the positive electrode active material layer 2 and the negative electrode active material layer 6 are coated on both surfaces of the strip-like positive electrode current collector foil 1 and negative electrode current collector foil 5. There is a case where the positive electrode 3 is made of a porous material that allows lithium ions to pass through, but is not limited thereto. In the figure, the lithium metal 9 is provided at the outermost periphery of the wound structure, but may be provided at the center. An example of the case where the lithium ion dope source is entrained in the same manner as the positive electrode 3 and the negative electrode 7, such as when the positive electrode 3 cannot pass through lithium ions, is described in Embodiment 4 described later.

  Hereinafter, the manufacturing method of the negative electrode 7 and LIC in Embodiment 1 of this invention is described in detail. FIG. 5 is a diagram showing a flow of manufacturing steps of the negative electrode 7 according to Embodiment 1 of the present invention. FIG. 6 is a diagram showing a flow of the manufacturing process of the LIC in the first embodiment of the present invention. Moreover, FIG. 7 is the figure which showed typically the press process of the negative electrode original fabric 21 in this Embodiment 1 of this invention. The basic structure and the manufacturing method are not different between the positive electrode 3 and the negative electrode 7, but the negative electrode 7 is different in that a step of forming the slit 4 is added.

  In FIG. 6, the manufacturing process of the positive electrode 3 in this embodiment will be described. The positive electrode 3 has the same configuration as a positive electrode of a general electric double layer capacitor. For example, a positive electrode material and a conductive auxiliary agent are rolled, coated, molded, etc. on a strip-shaped positive electrode current collector foil 1 made of an aluminum foil. Thus, the positive electrode active material layer 2 bound by the binder is formed. Here, a carbon material having a large surface area and a large capacitance is used as the positive electrode material. For example, it is particulate activated carbon having a diameter of about 10 μm, and water vapor activated activated carbon, alkaline activated carbon, nanogate carbon, and the like can be used. As the binder, a fluororesin such as PTFE (polytetrafluoroethylene), SBR (styrene butadiene rubber), acrylic synthetic rubber, PVDF (polyvinylidene fluoride), or the like is used. Then, it completes through processes, such as attachment of the positive electrode extraction part 12, etc. through a drying process and a press process. The positive electrode current collector foil 1 and the positive electrode active material layer 2 are configured with substantially the same area.

  Here, what applied the positive electrode active material layer 2 to the strip | belt-shaped positive electrode current collector foil 1, and dried it through the drying process is called the positive electrode original fabric 19. FIG. FIG. 14 is a schematic view schematically showing the pressing process of the positive electrode fabric 19. It should be noted that the components shown in parentheses in the figure indicate the third embodiment to be described later.

  5 and 7, the manufacturing process of the negative electrode 7 in this embodiment will be described. The manufacturing process of the negative electrode 7 in FIG. 5 is the same part extracted from FIG. The negative electrode 7 is formed with a notch 20 extending so as to penetrate at least one of the strip-shaped negative electrode current collector foil 5 made of, for example, copper foil so as to include a longitudinal component. Next, the negative electrode active material layer 6 in which the negative electrode material and the conductive additive are bound with a binder by a rolling method, a coating method, a molding method, or the like is applied. Here, as the negative electrode active material, a material capable of removing and inserting lithium by an electrochemical reaction, such as graphite, can be used, but is not limited thereto. In addition, it is possible to use a negative electrode material used as a negative electrode of a general lithium ion battery, such as amorphous carbon, tin, or a silicon alloy. The optimum thickness differs between the negative electrode 7 and the positive electrode 3 depending on the type of carbon used. Then, it completes through processes, such as attachment of the negative electrode extraction part 11, etc. through a drying process and a press process. The negative electrode current collector foil 5 and the negative electrode active material layer 6 are formed with substantially the same area.

  As is clear from FIG. 1, the negative electrode 7 obtained in this way includes a negative electrode current collector foil 5 provided with slits 4 and a negative electrode active material layer 6 provided with no slits 4. Here, the belt-shaped negative electrode current collector foil 5 is provided with a notch 20 and the negative electrode active material layer 6 is applied and then dried through a drying process. Hereinafter, it will be described as a negative electrode raw fabric 21 when necessary. Further, the difference between the slit 4 and the notch 20 is distinguished by whether or not it is cut out in a form having a width. Specifically, after forming the cut 20 with a cutter or the like, the width is expanded through a pressing process, and the slit 4 is formed. Strictly speaking, a notch width such as a blade width is formed for the notch 20, but it is not called the slit 4 because it is not a width that is consciously provided for the purpose of providing the width. In the present embodiment, after the cut 20 is provided, pressing is performed to widen the slit 4 to form the slit. However, after the slit 4 having a narrow width is intentionally provided, the pressing is performed to reduce the width. A wide slit 4 may be formed. Moreover, it cannot be overemphasized that the width | variety of the slit 4 formed can be adjusted by adjusting the temperature in the time of press work, a pressure, or tension | tensile_strength.

  The positive electrode 3 and the negative electrode 7 manufactured as described above are integrated with the separator 8 interposed therebetween. Here, the separator 8 separates the positive electrode 3 and the negative electrode 7 and allows lithium ions to pass through while ensuring insulation between the two electrodes. The separator 8 is made of, for example, polyethylene or polypropylene. In addition, a cellulose-based paper separator or the like may be used.

  Next, a lithium metal 9 that is a lithium ion dope source is placed through a negative electrode 7 and a separator 8.

  The LIC cell 18 thus obtained is accommodated in the outer container 17. Here, the outer container 17 is not particularly limited, but may be a cylindrical or square container made of a metal such as stainless steel or aluminum. Moreover, the bag-shaped or box-shaped container which consists of a laminate film comprised with a metal and resin may be sufficient. The container made of this laminate film can be sealed by heat sealing (heat sealing) as long as it can prevent leakage of the electrolyte from the inside of the LIC and intrusion of moisture from the outside of the LIC. Although a resin film having heat-fusibility can be used for the seal portion, it is preferable to deposit a metal, coat with metal plating, or laminate a metal foil such as aluminum. When a metal foil is used, it can be used alone if it has a sufficient thickness. However, in general, a resin foil laminated to a metal foil with a thickness of several to several tens of microns is used to reduce the weight. It is done. And it is preferable to laminate | stack the polyethylene terephthalate and stretched nylon film for an intensity | strength improvement on the outer surface, and the polyethylene or polypropylene film for providing heat-fusibility.

  Various methods can be used for forming the bag-like container. For example, a film cut into a square shape is folded in half and heat-sealed in three directions, and both openings of the film formed in a cylindrical shape are heat-sealed. The method etc. can be mentioned. The container material may be used as it is cut, but it can also be used after pressing a recess corresponding to the electrode body. Excess container material may be cut or bent after heat sealing.

Next, an electrolytic solution is injected into the outer container 17 and sealed. Here, the electrolyte solution is filled in the outer container 17, but is not shown because it is not directly related to the present invention. The electrolytic solution is not particularly limited, for _{example, LiPF 6, LIClO 4, LiBF} 4, LiAsF 6, LICF 3 SO 3, LiN (CF 3 SO 2) 2, LiN (C 2 F 5 SO 2) 2, LIC ( Examples thereof include an electrolyte such as CF ₃ SO ₂ ) ₃ dissolved in an organic solvent. Examples of organic solvents include ether solvents such as dimethoxyethane and diethyl ether, and ester solvents such as ethylene carbonate (EC), propylene carbonate (PC), ethyl methyl carbonate (MEC), dimethyl carbonate (DMC), and diethyl carbonate (DEC). Solvent, γ-butyrolactone (GBL), tetrahydrofuran (THF), tetrahydropyran (THP), 1,3-dioxane (DOX), ethyl dimethyl phosphate (EDMP), trimethyl phosphate (TMP), propyl dimethyl phosphate (PDMP) ) And the like, and these can be used alone or in combination of two or more.

Furthermore, the electrolyte solution may contain other additives. Examples of combinations are LiPF ₆ / EC + DEC, LiBF ₄ / EC + DEC, LiN (CF ₃ SO ₂ ) ₂ / EC + DEC, LiN (C ₂ F ₅ SO ₂ ) ₂ / EC + DEC, LiPF ₆ / EC + PC, LiPF ₆ / EC + GBL, LiBF ₄ / EC + PC, LiBF ₄ / EC + GBL, LiBF ₄ / EDMP, LiBF ₄ / EC + EDMP, LiN (CF ₃ SO ₂ ) ₂ / EC + GBL, LiN (C ₂ F ₅ SO ₂ ) ₂ / EC + GBL, LiN (CF ₃ SO ₂ ) ₂ / EC + EDMP, LiN (C ₂ F ₅ SO ₂ ) ₂ / EC + EDMP, and the like, but are not limited thereto. Further, in order to have ionic conductivity even at a high temperature of 100 ° C. or higher, the organic solvent desirably contains a high boiling point solvent such as EC, PC, GBL.

  Here, in order to lower the potential of the negative electrode 7 and make the lithium ion capacitor usable, it is necessary to dope the negative electrode 7 with lithium ions. In this embodiment, the negative electrode 7 is doped with lithium ions. 7 and lithium metal 9 installed via separator 8 is used as a dope source to diffuse lithium ions into the electrolyte and insert.

  In some cases, lithium metal oxide such as lithium cobaltate is used as a doping source instead of metallic lithium, and the doping is forced by charging from an external power source. As a doping source other than metallic lithium, for example, one or more of the materials of positive electrode 3 capable of inserting and extracting lithium ions are included, and a conductive material such as a carbon material and the like, if necessary. A binder such as polyvinylidene fluoride may be included. As a material for the positive electrode 3 capable of inserting and extracting lithium ions, lithium iron phosphate olivine phosphate and a lithium transition metal composite oxide containing lithium and a transition metal are preferable.

  In this embodiment, one or more slits 4 are formed as a path through which lithium ions diffuse in the negative electrode current collector foil 5 in order to transmit lithium ions. The slit 4 is obtained by opening the negative electrode original fabric 21 by pressing it at a predetermined temperature and pressure. Therefore, lithium ions can be transmitted efficiently.

  This pressing step can be performed by a flat plate press, but if it is performed by a roll-type press such as the calendar roll press, an electrode plate having a larger area can be efficiently pressed.

  Hereinafter, one example of the manufacturing method of the LIC in this embodiment will be described with specific numerical values, and results of comparing the performance of the obtained LIC with the following comparative examples will be shown.

  A method for manufacturing the positive electrode 3 using the positive electrode fabric 19 will be described. As the positive electrode current collector foil 1, a strip-shaped aluminum foil having a width of 300 mm and a thickness of 50 μm is used. An electrode paste composed of activated carbon as a positive electrode material, styrene butadiene polymer as a binder, and water as a solvent is mixed and prepared, and is formed on one side of a strip-shaped aluminum foil. Then, the positive electrode fabric 19 obtained through the drying process was pressurized at 105 ° C. with a calender roll press to adjust the porosity of the electrode.

  Here, since the positive electrode active material layer 2 has a larger expansion / contraction ratio than the positive electrode current collector foil 1, the positive electrode active material layer 2 expanded by pressing is also spread around the positive electrode current collector foil 1. Although the material layer 2 protrudes slightly, there is no particular influence.

  Thereafter, the positive electrode 3 is cut out into a rectangle having a side of 92 mm × 129 mm from the pressed positive electrode raw material 19, and the positive electrode active material layer 2 on the short side is peeled to form a positive electrode extraction part 12. The positive electrode connection terminal 13 was formed by sonic welding.

  FIG. 7 is a view schematically showing a pressing process of the negative electrode original fabric 21 in this embodiment. Hereinafter, a method for producing the negative electrode 7 using the negative electrode fabric 21 will be described. As the negative electrode current collector foil 5, a strip-shaped copper foil having a width of 300 mm and a thickness of 20 μm in which cuts 20 (0.08 mm) are formed at intervals of 5 mm is used. An electrode paste composed of graphite as a negative electrode material, polyvinylidene fluoride as a binder, and n-methylpyrrolidone as a solvent is mixed and prepared, and is coated on one side of a strip-shaped copper foil in which cuts 20 are formed. Then, the negative electrode raw fabric 21 obtained through the drying process was pressurized at 105 ° C. with a calender roll press to adjust the porosity of the electrode. The opening width of the notch 20 before pressing was 0.08 mm, whereas the opening width of the notching 20 after pressing was increased to 0.16 mm, and the slit 4 was formed.

  The reason why the slits 4 are formed by expanding the opening width of the cuts 20 to about twice after the calendar roll press is due to the fact that the negative electrode current collector foil 5 and the negative electrode active material layer 6 have different expansion ratios. This is because the negative electrode active material layer 6 has a larger expansion ratio than the negative electrode current collector foil 5, so that the negative electrode active material layer 6 expanded by pressing slips under the negative electrode current collector foil 5 and widens the cut 20. In addition, although the negative electrode active material layer 6 pushed out also slightly around the negative electrode current collector foil 5 protrudes, there is no particular influence.

  Thereafter, the negative electrode 7 is cut out from the pressed negative electrode raw material 21 into a rectangle having a side of 92 mm × 129 mm, and the negative electrode active material layer 6 on the short side is peeled off to form a negative electrode extraction part 14. Were connected by ultrasonic welding to form a negative electrode connection terminal 16.

The positive electrode 3 and the negative electrode 7 were aligned so that the active material layers face each other, and a cellulose paper separator 8 having a thickness of 40 μm was sandwiched therebetween. A rectangular metal lithium foil having a thickness of 30 μm and a side of 60 mm × 80 mm was stacked as the metal lithium 8 on the copper foil on the back surface of the negative electrode 7, and the whole was accommodated in the exterior of an aluminum laminate film as the exterior container 17. The laminated electrode was injected with an ethylene carbonate-diethyl carbonate 3: 7 mixed solvent containing 1.2 mol / l LiPF ₆ as an electrolytic solution, and finally the aluminum laminate outer package, which is the outer container 17, was sealed, and the capacitor cell ( The LIC before lithium ion insertion is shown). Thereafter, in order to promote the insertion of lithium ions into the negative electrode 7, the capacitor cell was aged for 7 days in a thermostat at 50 ° C.

  About this LIC, the charge / discharge test was done by the lower limit voltage 2.0V and the upper limit voltage 4.0V in the environment of room temperature 25 degreeC. Table 1 shows discharge capacities when the discharge current is changed between the test results and the test results of Comparative Examples 1 to 6 shown below. From the results in Table 1, the superiority of the performance of the LIC according to this embodiment is clear.

(Comparative Example 1)
(Production method of Comparative Example 1)
As the negative electrode current collector foil, an expanded metal having a width of 300 mm, a thickness of 30 μm, and an aperture ratio of 55% was used, and a paste produced in the same manner as in the above embodiment was applied, but the paste penetrated into the opening of the expanded metal, A predetermined amount of active material could not be obtained. Since the amount of the active material became a predetermined amount by performing the coating again, the negative electrode raw material was pressed at 105 ° C. with a calendar roll press to adjust the porosity of the electrode. The negative electrode raw material after pressing is cut into a rectangle having a side of 92 mm × 129 mm, the negative electrode active material layer on the short side is peeled off to form a negative electrode extraction part, and a Ni-plated copper foil is connected to the negative electrode extraction part by ultrasonic welding to form a negative electrode The connection terminal. The positive electrode production and the LIC cell production method of this comparative example were the same as those in the above embodiment.

(Comparative Example 2)
(Production method of Comparative Example 2: When notch is not widened)
As a negative electrode current collector foil, a paste prepared in the same manner as in the above embodiment was applied without forming a slit on a copper foil having a width of 300 mm and a thickness of 20 μm to produce a negative electrode original fabric. The negative electrode raw material was pressed at 105 ° C. with a calender roll press to adjust the porosity of the electrode. Then, the negative electrode raw material after pressing was cut at intervals of 5 mm. The negative electrode raw material after pressing was cut into a rectangle of 92 mm × 129 mm on one side, the negative electrode active material layer on the short side was peeled off to form a negative electrode extraction part, and Ni-plated copper foil was connected to this negative electrode extraction part by ultrasonic welding. It was set as the negative electrode connection terminal. The positive electrode production and the LIC cell production method of this comparative example were the same as those in the above embodiment.

(Comparative Example 3)
(Production method of Comparative Example 3: When the opening area of the slit is small)
As a negative electrode current collector foil, a paste prepared in the same manner as in the above embodiment was applied without forming a slit on a copper foil having a width of 300 mm and a thickness of 20 μm to produce a negative electrode original fabric. The negative electrode raw material was pressed at 105 ° C. with a calender roll press to adjust the porosity of the electrode. Thereafter, ten slits having an opening width of 0.08 mm and a length of 10 mm were formed per 100 cm 2 on the negative electrode raw material after pressing. The negative electrode raw material after pressing was cut into a rectangle of 92 mm × 129 mm on one side, the negative electrode active material layer on the short side was peeled off to form a negative electrode extraction part, and Ni-plated copper foil was connected to this negative electrode extraction part by ultrasonic welding. It was set as the negative electrode connection terminal. The positive electrode production and the LIC cell production method of this comparative example were the same as those in the above embodiment.

(Comparative Example 4)
(Production method of Comparative Example 4: When the opening area of the slit is large)
As a negative electrode current collector foil, cuts 20 (1.0 mm) were formed at intervals of 5 mm in a strip-shaped copper foil having a width of 300 mm and a thickness of 20 μm, and a paste prepared in the same manner as in the above embodiment was applied. The negative electrode raw material was pressed at 105 ° C. with a calender roll press to adjust the porosity of the electrode. The opening width of the slit after pressing was 1.1 mm, and the opening ratio with respect to the electrode area was 12%. After that, the negative electrode raw material after pressing is cut into a rectangle having a side of 92 mm × 129 mm, the negative electrode active material layer on the short side is peeled off to form a negative electrode extraction part, and Ni-plated copper foil is connected to the negative electrode extraction part by ultrasonic welding. Thus, a negative electrode connection terminal was obtained. The positive electrode production and the LIC cell production method of this comparative example were the same as those in the above embodiment.

(Comparative Example 5)
(Production method of Comparative Example 5: When the slit interval is 10 mm or more)
As a negative electrode current collector foil, a paste prepared in the same manner as in the above embodiment was applied without forming a slit on a copper foil having a width of 300 mm and a thickness of 20 μm to produce a negative electrode original fabric. Cuts were formed in the negative electrode raw material at intervals of 11 mm, and thereafter, the calender roll was pressurized at 105 ° C. to adjust the porosity of the electrode. The opening width of the slit after pressing was 30 μm. The negative electrode raw material after pressing was cut into a rectangle of 92 mm × 129 mm on one side, the negative electrode active material layer on the short side was peeled off to form a negative electrode extraction part, and Ni-plated copper foil was connected to this negative electrode extraction part by ultrasonic welding. It was set as the negative electrode connection terminal. The positive electrode production and the LIC cell production method of this comparative example were the same as those in the above embodiment.

(Comparative Example 6)
(Production method of Comparative Example 6: when the press temperature is 90 ° C.)
As a negative electrode current collector foil, a paste prepared in the same manner as in the above embodiment was applied without forming a slit on a copper foil having a width of 300 mm and a thickness of 20 μm to produce a negative electrode original fabric. Cuts were formed in the negative electrode original fabric at intervals of 5 mm, and then the porosity of the electrode was adjusted by pressing at 90 ° C. with a calender roll press. The opening width of the slit after pressing was 0.1 mm. The negative electrode raw material after pressing was cut into a rectangle of 92 mm × 129 mm on one side, the negative electrode active material layer on the short side was peeled off to form a negative electrode extraction part, and Ni-plated copper foil was connected to this negative electrode extraction part by ultrasonic welding. It was set as the negative electrode connection terminal. The positive electrode production and the LIC cell production method of this comparative example were the same as those in the above embodiment.

Embodiment 2. FIG.
In the manufacturing method of the negative electrode 7 in the first embodiment, the slit 4 is formed by expanding the opening width by press working on the negative electrode raw material 21 in which the cut 20 is made in the negative electrode current collector foil 5. The same effect can be obtained even if the slits 4 are formed by pressing and forming the slits 4 by forming the slits 20 in the negative electrode raw material 21 without providing the slits 20 in the electric foil 5. can get. FIG. 8 is a diagram showing a flow of a negative electrode manufacturing process in the second embodiment of the present invention. FIG. 9 is a diagram showing a flow of a manufacturing process of a lithium ion capacitor (hereinafter sometimes referred to as LIC) in the second embodiment of the present invention. FIG. 10 is a diagram showing a part of the cross section of the LIC in the second embodiment of the present invention. Since the main difference from the first embodiment is related to the manufacturing process of the negative electrode 7, the manufacturing process of the negative electrode 7 will be mainly described here, and the other parts are the same as those of the first embodiment. Since there is, explanation is omitted. The manufacturing method of the negative electrode 7 in this embodiment is as follows.

  In FIG. 8, the manufacturing process of the negative electrode 7 in this embodiment will be described. The manufacturing process of the negative electrode 7 in FIG. 8 is the same part extracted from FIG. For example, the negative electrode active material layer 6 in which a negative electrode material and a conductive additive are bound with a binder by a rolling method, a coating method, a molding method, or the like is applied to a strip-shaped negative electrode current collector foil 5 made of copper foil. Here, as the negative electrode material, a material capable of removing and inserting lithium by an electrochemical reaction, such as graphite, can be used, but the material is not limited thereto. In addition, it is possible to use a negative electrode material used as a negative electrode of a general lithium ion battery, such as amorphous carbon, tin, or a silicon alloy. The optimum thickness differs between the negative electrode 7 and the positive electrode 3 depending on the type of carbon used. After that, the negative electrode raw material 21 obtained through the drying process is extended so as to include the longitudinal component, and a cut 20 is formed so as to penetrate at least one. Next, it passes through a press process, and completes through processes, such as attachment of the negative electrode extraction part 11, etc. Here, the negative electrode current collector foil 5 and the negative electrode active material layer 6 are formed with substantially the same area.

  As is clear from FIG. 8, the negative electrode 7 thus obtained is composed of a negative electrode current collector foil 5 and a negative electrode active material layer 6 each having a slit 4. In addition, the slit 4 provided in the negative electrode active material layer 6 has a center substantially the same (substantially concentric) as compared with the slit 4 provided in the negative electrode current collector foil 5, and the width (the negative electrode 7 is the same as that of the slit 4. When the end portion is included, the slit has a short width and length. This is apparent from the fact that the negative electrode active material layer 6 has a larger expansion / contraction rate than the negative electrode current collector foil 5 as described above. Hereinafter, one example of the manufacturing method of the negative electrode 7 of the LIC in this embodiment will be described with specific numerical values, and the performance of the LIC manufactured using the negative electrode 7 will be compared with the plurality of comparative examples. The results are shown.

  A negative electrode current collector foil 5 was prepared by mixing an electrode paste made of graphite as a negative electrode material, polyvinylidene fluoride as a binder, and n-methylpyrrolidone as a solvent in a strip-shaped copper foil having a width of 300 mm and a thickness of 20 μm. Coating is formed on one side of the copper foil. Thereafter, the negative electrode raw material 21 obtained through the drying process is extended so as to include the longitudinal component, and cuts 20 (0.08 mm) are formed at intervals of 5 mm so as to penetrate at least one. The negative electrode fabric 21 provided with the cut 20 was pressed at 105 degrees with a calender roll press to adjust the porosity of the electrode. The opening width of the notch 20 before pressing was 0.08 mm, whereas the opening width of the notching 20 after pressing was increased to 0.14 mm, and the slit 4 was formed.

  The reason why the slits 4 are formed by expanding the opening width of the cuts 20 to about twice after the calendar roll press is due to the fact that the negative electrode current collector foil 5 and the negative electrode active material layer 6 have different expansion ratios. This is because the negative electrode active material layer 6 has a larger expansion ratio than the negative electrode current collector foil 5, so that the negative electrode active material layer 6 expanded by pressing slips under the negative electrode current collector foil 5 and widens the cut 20. In addition, although the negative electrode active material layer 6 pushed out also slightly around the negative electrode current collector foil 5 protrudes, there is no particular influence. In addition, the negative electrode active material layer 6 is also formed with slits 4 that are narrower than the negative electrode current collector foil 5, and these are slits 4 that are mainly formed by the compressive force and tensile force of the press.

  FIG. 7 is a diagram schematically showing the pressing process of the negative electrode original fabric 21 in the first embodiment, but there is a difference when the pressing process of the negative electrode original fabric 21 in the second embodiment is also schematically expressed. There is no. The length and width of the slit 4 provided after pressing are not particularly specified, but the area of the opening is preferably 0.1% or more and 10% or less with respect to the area of the negative electrode 7. Moreover, it is preferable that the space | interval of adjacent slits 4 is less than 10 mm. The direction of the slit 4 with respect to the direction of rotation of the roll at the time of pressing is not particularly specified. For example, when performing roll pressing as shown in FIG. 7, the longitudinal direction of the slit 4 with respect to the direction of rotation of the roll at the time of pressing. Is preferably vertical or obliquely 30 degrees or more. This is because the cut 20 is substantially perpendicular to the rotation direction of the roll during pressing, and pressure is applied to the entire cut 20 at the same time, so that the slit width is efficiently widened. On the contrary, when the negative electrode layer 11 provided with the slit is used to form a wound structure, it is preferable that the negative electrode layer 11 is parallel to the wound (longitudinal) direction or less than 30 degrees obliquely. This is because the slit 4 opens more than necessary due to the tension at the time of winding and after pressing, which may cause a winding slip or the like.

  Thereafter, the negative electrode 7 is cut out from the pressed negative electrode raw material 21 into a rectangle having a side of 92 mm × 129 mm, and the negative electrode active material layer 6 on the short side is peeled off to form a negative electrode extraction part 14. Were connected by ultrasonic welding to form a negative electrode connection terminal 16.

  The negative electrode 7 thus obtained is structurally different from the negative electrode 7 obtained in the first embodiment in that the negative electrode active material layer 6 is also provided with a through hole. There is a slight difference in performance. FIG. 10 is a diagram showing a part of a cross section of the LIC in the second embodiment of the present invention. In addition, since parts other than the negative electrode 7 are the same as those in the first embodiment, description thereof is omitted.

  Next, the LIC in this embodiment was subjected to a charge / discharge test at a lower limit voltage of 2.0 V and an upper limit voltage of 4.0 V in an environment at room temperature of 25 ° C. Table 2 shows the discharge capacity when the discharge current is changed between the test results and the LIC test results of the first embodiment and the LICs of the plurality of comparative examples. From the results of Table 2, the superiority of the performance of the LIC according to this embodiment over other comparative examples is clear.

  In Comparative Example 1, since expanded metal is used as the negative electrode current collector foil, the current density of the current collector foil increases when discharged at a high current, and current collection becomes insufficient, so that sufficient capacity can be obtained. There wasn't. In Comparative Example 2, since the slit was formed after the negative electrode plate was pressed, the lithium ions were not uniformly doped, and a sufficient discharge capacity could not be obtained. Further, in Comparative Example 3, since the slit aperture ratio was as small as less than 0.1% of the electrode area, ion doping was not uniform and sufficient discharge capacity could not be obtained. In Comparative Example 4, since the slit aperture ratio was as large as 12% of the electrode area, the electrode reaction area was reduced and a sufficient discharge capacity could not be obtained. Further, in Comparative Example 5, since the gap between the slits was as large as 10 mm or more, ion doping was uneven and insufficient, and a sufficient discharge capacity could not be obtained. In Comparative Example 6, since the negative electrode plate was pressed at a low temperature and the slit opening after pressing was insufficient, ion doping was uneven and sufficient discharge capacity could not be obtained.

Embodiment 3 FIG.
In the second embodiment, metallic lithium is used as the lithium ion doped layer. In the third embodiment, cobalt is used as the active material on the aluminum foil having a thickness of 20 μm as the lithium ion doped layer current collector foil 22. Lithium acid, acetylene black as a conductive additive, and a binder coated with an active material layer paste obtained by dispersing polyvinylidene fluoride in NMP as a dispersion medium are used as a lithium ion doping source. . Since other parts are the same as those of the above embodiment, the description thereof is omitted. The manufacturing method of the doped layer of lithium ions in this embodiment is as follows.

  FIG. 11 is a diagram showing a part of a cross section of a lithium ion capacitor (hereinafter sometimes referred to as LIC) in Embodiment 3 of the present invention. In the figure, the lithium ion doped layer 23 is manufactured as follows.

  On the 20 μm thick aluminum foil as the lithium ion doped layer current collector foil 22, lithium cobaltate as an active material, acetylene black as a conductive auxiliary agent, and polyvinylidene fluoride as a binder are dispersed in NMP as a dispersion medium. The obtained active material layer paste was applied and dried at 100 ° C., and then a lithium ion doped layer original fabric 24 having a thickness of about 100 μm was obtained. Thereafter, the lithium ion doped layer raw material 24 is pressed at 105 ° C. with a calendar roll press to a thickness of about 70 μm. The pressed lithium ion doped layer raw fabric 24 is cut into a rectangle of 90 mm × 127 mm on one side, and the current collector on the short side is stretched to form a lithium doped electrode extraction part 15, and an aluminum foil is applied to the lithium doped electrode extraction part 15. Lithium ion doped electrode terminals 25 were connected by ultrasonic welding. Note that the pressing process of the lithium ion doped layer original fabric 24 is the same as the pressing process of the positive electrode original fabric 19 and is therefore substituted in FIG. In addition, the component shown in the parenthesis in the figure indicates the third embodiment.

The positive electrode 3 and the negative electrode 7 were aligned so that the active material layers face each other, and a cellulose paper separator 8 having a thickness of 40 μm was sandwiched therebetween. The lithium ion doped layer 23 was overlaid on the copper foil on the back surface of the negative electrode 7, and the whole was accommodated in the exterior of an aluminum laminate film as the exterior container 17. This laminated electrode was injected with an ethylene carbonate-diethyl carbonate 3: 7 mixed solvent containing 1.2 mol / l LiPF ₆ as an electrolytic solution, and finally the aluminum laminate outer package as the outer container 17 was sealed. The capacitor in the form of was completed. Thereafter, in order to promote the insertion of lithium ions into the negative electrode 7, the lithium doped electrode extraction part 15 of the lithium ion doped layer 23 is connected to the lithium ion electrode terminal 25, and the negative electrode extraction part 14 is connected to the positive terminal of the charging / discharging device. It connected to the terminal, CC-CV charge to 4.0V was performed at 1 mA, and the negative electrode 7 was doped with lithium ions.

  For the LIC obtained in this embodiment, the same test as in the above embodiment was performed and the results are shown in Table 3. From the results shown in Table 3, the LIC according to this embodiment is clearly superior to other comparative examples in the same manner as the LIC according to the other embodiments.

Embodiment 4 FIG.
In the third embodiment, the card-type LIC cell 18 is composed of a pair of rectangular positive electrode 3, negative electrode 7, and separator 8. In the present embodiment, a LIC cell 18 having a wound structure is shown. FIG. 12 is a diagram showing a part of a cross section of a lithium ion capacitor (hereinafter also referred to as LIC) in the fourth embodiment of the present invention. FIG. 13 is a schematic diagram of the LIC cell 18 according to the fourth embodiment of the present invention. Hereinafter, a method of manufacturing the LIC in the present embodiment will be described. In addition, since the manufacturing method of the negative electrode original fabric 21 is the same as that of the said Embodiment 1, description is abbreviate | omitted here. Hereinafter, a manufacturing method of the positive electrode 3 and the lithium ion doped layer 23 in the present embodiment will be described.

  As the positive electrode current collector foil 1, a strip-shaped aluminum foil having a width of 300 mm and a thickness of 50 μm is used. An electrode paste made of activated carbon as a positive electrode material, styrene butadiene polymer as a binder, and water as a solvent is mixed and prepared, and applied to one side of a strip-shaped aluminum foil to form the positive electrode active material layer 2. Thereafter, the positive electrode fabric 19 obtained through the drying process was pressurized at 105 ° C. with a calender roll press to adjust the porosity of the positive electrode 3. Thereafter, in this positive electrode 3, lithium cobalt oxide, acetylene black and PVDF are dispersed in NMP as a lithium ion doped layer 23 on the opposite surface across the positive electrode active material layer 2 and the positive electrode current collector foil 1 and dried at 100 ° C. Thereafter, a doped layer having a thickness of 100 μm was obtained. Thereafter, the porosity is adjusted by roll pressing, and the porosity is cut into a size of 248 mm × 46 mm. The positive electrode active material layer 2 having an end portion of 10 mm in the longitudinal direction is peeled off, and the foil portion is exposed to expose the positive electrode. It was set to 12. An aluminum terminal was connected to the positive electrode take-out portion 12 by spot welding to form a positive electrode connection terminal 13.

  The negative electrode fabric 21 obtained in the same manner as in the first embodiment was pressed, cut into a size of 262 mm × 50 mm, and the negative electrode active material layer 6 having an end portion 10 mm in the longitudinal direction was peeled only on one side to obtain a foil. The part was exposed to form a negative electrode takeout part 14. A nickel plate having a thickness of 0.1 mm with a fusing material attached to the negative electrode take-out portion 14 was joined by spot welding to form a negative electrode connection terminal 16.

After each member is sufficiently dried, the positive electrode 3 and the negative electrode 7 are faced each other so that the positive electrode active material layer 2 and the negative electrode active material layer 6 face each other, and a separator 8 is sandwiched therebetween to overlap each other. Turned and fixed with tape. This is put in an outer bag made of an aluminum laminate sheet, and an ethylene carbonate-diethyl carbonate 3: 7 mixed solvent containing 1.2 mol / l LiPF ₆ is injected as an electrolytic solution. The aluminum laminate exterior was sealed to complete the LIC in this embodiment. Thereafter, in order to promote the insertion of lithium ions into the negative electrode 7, the positive electrode extraction part 12 of the lithium ion doped layer 23 is connected to the positive terminal of the charging / discharging device, and the negative electrode extraction part 14 is connected to the negative electrode connection terminal 16 at 4 mA at 1 mA. CC-CV charge up to 0.0 V was performed, and the negative electrode 7 was doped with lithium ions.

  Thereafter, charging and discharging were performed at a predetermined current. In this embodiment, since the lithium ion doped layer 23 using lithium cobaltate contributes not only to doping but also to electrode reaction, a large capacity can be obtained.

It is a figure which shows a part of cross section of the lithium ion capacitor (henceforth LIC) in Embodiment 1 of this invention. It is sectional drawing which shows the structure of the LIC cell in Embodiment 1 of this invention. It is sectional drawing which shows the structure of the LIC cell in Embodiment 1 of this invention. It is sectional drawing which shows the winding structure of LIC in Embodiment 1 of this invention. It is a figure which shows the flow of the manufacturing process of the negative electrode in Embodiment 1 of this invention. It is a figure which shows the flow of the manufacturing process of LIC in Embodiment 1 of this invention. It is the figure which showed typically the press process of the negative electrode original fabric in this Embodiment 1. FIG. It is a figure which shows the flow of the manufacturing process of the negative electrode in Embodiment 2 of this invention. It is a figure which shows the flow of the manufacturing process of LIC in Embodiment 2 of this invention. It is a figure which shows a part of cross section of LIC in Embodiment 2 of this invention. It is a figure which shows a part of cross section of LIC in Embodiment 3 of this invention. It is a figure which shows a part of cross section of LIC in Embodiment 4 of this invention. It is the schematic of the LIC cell in Embodiment 4 of this invention. It is the figure which showed typically the press process of the positive electrode original fabric in Embodiment 1 of this invention, and the lithium ion dope layer original fabric in Embodiment 3 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Positive electrode current collection foil, 2 Positive electrode active material layer, 3 Positive electrode, 4 slits, 5 Negative electrode current collection foil, 6 Negative electrode active material layer, 7 Negative electrode, 8 Separator, 9 Lithium metal, 10 Positive electrode layer, 11 Negative electrode layer, 12 Positive electrode Extraction part, 13 Positive electrode connection terminal, 14 Negative electrode extraction part, 15 Lithium doped electrode extraction part, 16 Negative electrode connection terminal, 17 Outer container, 18 LIC cell, 19 Positive electrode fabric, 20 Notch, 21 Negative electrode fabric, 22 Lithium ion dope Layer current collector foil, 23 Lithium ion doped layer, 24 Lithium ion doped layer raw fabric, 25 Lithium ion electrode terminal

Claims (8)

A negative electrode in which a negative electrode active material layer having a substantially the same area is provided on at least one surface of a negative electrode current collector foil, wherein at least one slit having a longitudinal component is formed only in the negative electrode current collector foil. Negative electrode. A negative electrode in which a negative electrode active material layer having a substantially the same area is provided on at least one surface of a negative electrode current collector foil, and at least one slit having a longitudinal component in both the negative electrode current collector foil and the negative electrode active material layer The slits in the negative electrode current collector foil and the slits in the negative electrode active material layer have substantially different widths, and the slit width in the negative electrode active material layer is the slit width in the negative electrode current collector foil Negative electrode characterized by being narrower. A lithium ion capacitor comprising an electrolyte together with a positive electrode and a negative electrode, wherein the negative electrode is provided with a negative electrode active material layer having substantially the same area on at least one surface of the negative electrode current collector foil, and a longitudinal component is provided only on the negative electrode current collector foil. A lithium ion capacitor having at least one slit formed therein. A lithium ion capacitor including an electrolyte together with a positive electrode and a negative electrode, wherein the negative electrode is provided with a negative electrode active material layer having substantially the same area on at least one surface of the negative electrode current collector foil, and the negative electrode current collector foil and the negative electrode active material layer In each case, at least one slit having a longitudinal component is formed, the slit in the negative electrode current collector foil and the slit in the negative electrode active material layer have concentrically different widths, and the negative electrode active material layer The lithium ion capacitor is characterized in that the slit width in is narrower than the slit width in the negative electrode current collector foil. A method for producing a negative electrode in which a negative electrode active material layer is formed on at least one surface of a negative electrode current collector foil, wherein at least one penetrating portion cut into the negative electrode current collector foil has a longitudinal component Forming the negative electrode active material layer with substantially the same area on at least one surface of the negative electrode current collector foil, and a subsequent pressing step to expand the penetrating portion with the area expansion of the negative electrode active material layer. The method for producing a negative electrode according to claim 1. A method for producing a negative electrode in which a negative electrode active material layer is formed on at least one surface of a negative electrode current collector foil, the step of forming the negative electrode active material layer with substantially the same area on at least one surface of the negative electrode current collector foil, and the negative electrode A step of forming at least one penetrating portion having a longitudinal component formed so as to penetrate through the current collector foil and the negative electrode active material layer, and a subsequent pressing step to form the through portion into the negative electrode current collecting foil and The method for producing a negative electrode according to claim 2, wherein the negative electrode active material layer is expanded as the area of the negative electrode active material layer increases. A method for manufacturing a lithium ion capacitor comprising an electrolyte together with a positive electrode and a negative electrode, wherein the method for manufacturing the negative electrode is the manufacturing method according to claim 5. A method for producing a lithium ion capacitor comprising an electrolyte together with a positive electrode and a negative electrode, wherein the method for producing the negative electrode is the production method according to claim 6.

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